Modifying objects in stencil

[MrD1sturbed]

I created a copy of the Programming Flow Chart stencil so that I could add an Internal Storage object like the one available from Google Docs Drawing tool. I can not figure out how to add the needed strokes to the object's interior to create the same object available from Google. In other words I want to create the same type of object as the "Predefined Process", but I want the inside strokes to be like that of the Google Docs object. I have added a screenshot below to illustrate what I want to create. Any help would be GREATLY appreciated.

I'm using OmniGraffle Pro ver. 5.3.6.

http://content.screencast.com/users/Ccarter79FSO/folders/Jing/media/af6f69d2-987b-40c5-9035-6ac902ca9ce2/00000038.png